Yeah sure SP has the weapon wheel but there's a reason why the weapon wheel activates bullet time, which ohviously can't be done in MP.
TBH, a 2 weapon limit game with weapon pickups would be really interesting to watch as now you no longer have to fumble your hands through the 1-6 keys to get the gun that you want.

But newbies aren't really trained to memorize and anticipate the pickups right now as they already have the good guns, so with stashing away the good guns (RL/Plasma/Lightning/SSG) newbies would be more motivated to learn spawn times, and it also placates the "hurr durr loadouts" somewhat.

Loadouts by themselves aren't that bad as they let you pick a playstyle that you like from the start, but they should only let you pick the weaker guns (Shotgun/Static Cannon/HAR/Vortex) and scatter the more powerful ones on the map (RL/SSG/Lightning Gun/Plasma) so that there's real map control involved.

Remember, the FoV in the beta is locked to 80 so the game would definititely feel faster when you jack it up to 100/110.
IMO, they need to fix these things before the game comes out soon or else :
1. Buff the weapon sounds
2. Add music while playing
3. Nerf the Gauss Cannon (take out the wall hack, and make the primary fire just the 150-damage rail itself without splash, to get the explosion use the secondary fire which costs 2 ammo)
4. Add damage knock back (yes it's annoying but it allows for some neat strats like damage surfing)
5. Allow us to turn off the damage numbers (like in TF2)
6. Add a mutator that turns off loadouts and just start you off with the pistol and shotgun and have everything else be a pickup.

It'll be really fun if you can influence the scripted sequences, for example say you can talk to a scientist that's behind a glass door to open a blast door in front of you that takes 3 minutes to open, you can either wait it out, or shoot the scientist to get his special secret key that lets you open a shortcut that bypasses the door.